Relation "migratehistory" already exists

[Tumetsu]

When I try to run all unapplied migrations, I get the following error:

peewee.ProgrammingError: relation "migratehistory" already exists

My python script to run all migrations:

db_connection.init_database()
db_connection.connect()
database = db_connection.get_database()

router = Router(database)

# Run all unapplied migrations
router.run()

After quick investigation to the source of peewee_migrate I found this from BaseRouter:

    @cached_property
    def model(self):
        """Initialize and cache MigrationHistory model."""
        MigrateHistory._meta.database = self.database
        MigrateHistory._meta.db_table = self.migrate_table
        MigrateHistory.create_table(True)
        return MigrateHistory

Looks like it tries to create the table always because of the last line before return which then fails if I have already migrated something to the db and the table exists. Why is that? Am I using this wrong somehow?

My peewee and peewee_migrate versions:

peewee==2.8.5
peewee-migrate==0.12.3

Using Python 3.5

And full stack trace:

Traceback (most recent call last):
  File "/home/tuomas/Code/KarjalaProject/karelian-db/karelian-db_venv/lib/python3.5/site-packages/peewee.py", line 3768, in execute_sql
    cursor.execute(sql, params or ())
psycopg2.ProgrammingError: relation "migratehistory" already exists


During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.5/runpy.py", line 184, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/lib/python3.5/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/home/tuomas/Code/KarjalaProject/karelian-db/tasks/migrate.py", line 12, in <module>
    router.run()
  File "/home/tuomas/Code/KarjalaProject/karelian-db/karelian-db_venv/lib/python3.5/site-packages/peewee_migrate/router.py", line 163, in run
    diff = self.diff
  File "/home/tuomas/Code/KarjalaProject/karelian-db/karelian-db_venv/lib/python3.5/site-packages/peewee_migrate/router.py", line 57, in diff
    done = set(self.done)
  File "/home/tuomas/Code/KarjalaProject/karelian-db/karelian-db_venv/lib/python3.5/site-packages/peewee_migrate/router.py", line 52, in done
    return [mm.name for mm in self.model.select()]
  File "/home/tuomas/Code/KarjalaProject/karelian-db/karelian-db_venv/lib/python3.5/site-packages/cached_property.py", line 26, in __get__
    value = obj.__dict__[self.func.__name__] = self.func(obj)
  File "/home/tuomas/Code/KarjalaProject/karelian-db/karelian-db_venv/lib/python3.5/site-packages/peewee_migrate/router.py", line 42, in model
    MigrateHistory.create_table(True)
  File "/home/tuomas/Code/KarjalaProject/karelian-db/karelian-db_venv/lib/python3.5/site-packages/peewee.py", line 4975, in create_table
    db.create_table(cls)
  File "/home/tuomas/Code/KarjalaProject/karelian-db/karelian-db_venv/lib/python3.5/site-packages/peewee.py", line 3852, in create_table
    return self.execute_sql(*qc.create_table(model_class, safe))
  File "/home/tuomas/Code/KarjalaProject/karelian-db/karelian-db_venv/lib/python3.5/site-packages/peewee.py", line 3775, in execute_sql
    self.commit()
  File "/home/tuomas/Code/KarjalaProject/karelian-db/karelian-db_venv/lib/python3.5/site-packages/peewee.py", line 3598, in __exit__
    reraise(new_type, new_type(*exc_args), traceback)
  File "/home/tuomas/Code/KarjalaProject/karelian-db/karelian-db_venv/lib/python3.5/site-packages/peewee.py", line 135, in reraise
    raise value.with_traceback(tb)
  File "/home/tuomas/Code/KarjalaProject/karelian-db/karelian-db_venv/lib/python3.5/site-packages/peewee.py", line 3768, in execute_sql
    cursor.execute(sql, params or ())
peewee.ProgrammingError: relation "migratehistory" already exists

[Tumetsu]

After some tinkering I found that the following modification seems to work:

@cached_property
    def model(self):
        """Initialize and cache MigrationHistory model."""
        MigrateHistory._meta.database = self.database
        MigrateHistory._meta.db_table = self.migrate_table
        self.database.create_table(MigrateHistory, safe=True)
        return MigrateHistory

and I posted an issue about it to peewee's repo: coleifer/peewee#1314

[Tumetsu]

Ok, I found the issue. Problem was that I have multiple schemas in my database and at the moment peewee_migrate seems to add migratehistorytable to first schema, in my case to schema extensions. Now since 'MigrateHistorydoes not specify meta optionschema peewee's table_exists function fails because its implementation requires schema to be set:

@classmethod
    def table_exists(cls):
        kwargs = {}
        if cls._meta.schema:
            kwargs['schema'] = cls._meta.schema
        return cls._meta.db_table in cls._meta.database.get_tables(**kwargs)

So for now the solution is to add following to the MigrateHistory model:

    class Meta:
        schema = 'schema_name'

This is a bit dirty however. Would it be possible to somehow configure MigrateHistorymodel to pass it the schema option?

[klen]

Hello @Tumetsu,

Good point. Sorry for the late response, but I've added schema param to Router. And now the option is configurable.